BLUE HILL METEOROLOGICAL OBSERVATORY MILTON, MASSACHUSETTS ELEVATION 635 FEET, 10 MILES SSW OF BOSTON, MA DAILY DISCUSSION AND CLIMATE SUMMARY SATURDAY, MAY 21, 2016 ALL TIMES ARE IN EASTERN STANDARD TIME HAZY SUNSHINE THIS MORNING DUE TO LINGERING SMOKE ALOFT... CLOUDS ADVANCED ALL MORNING AND COVERED THE SKY BY LATE MORNING AS WEAK STORM APPROACHES FROM THE SOUTHWEST... High clouds were already advancing into a very sunny sky early this morning. Haze and smoke aloft continued to filter the sunshine somewhat until cirrostratus, then lower altostratus and altocumulus moved in. For a time, cirrocumulus undulatus were observed overhead around mid-morning. The dew point dropped into the middle 30's by late morning as drier air mixed down to the surface from above, and this helped to raise the visibility from 45 miles to nearly 70 miles by the 1 PM EDT observation. Today's Observations: 7 A.M. Weather: Thin scattered cirrus, hazy, haze and smoke aloft Temperature: 60F; Dew Point: 43F; Wind: W at 10 kts Sea-level pressure: 30.17 ins. Hg, rising, then falling Visibility: 45 miles 6-hr Max temp: 60F 6-hr Min temp: 53F 24-hr precip: 0.00 in. BHO SA 1155 250 -SCT 45 217/60/43/2610/017/ HAZY HZ/K LYR ALF/ 8/001 50001 10060 20053 10 A.M. Weather: Scattered altocumulus, scattered cirrostratus, thin overcast cirrus fibratus, few small cumulus forming all quadrants, few altocumulus lenticularis, few cirrocumulus undulatus overhead, hazy Temperature: 73F; Dew Point: 36F; Wind: S at 8 kts, Sea-level pressure: 30.13 ins. Hg, falling Visibility: 45 miles BHO SA 1455 180 SCT 200 SCT 250 -OVC 45 203/73/36/1808/013/ FEW SML CU FRMG ALQDS FEW ACSL OVHD FEW CC OVHD HAZY/ 8/137 56014 1 P.M. Weather: Scattered altocumulus, overcast altostratus, few cumulus distant WNW-N, higher clouds visible distant W-NNE, sun dimly visible Temperature: 69F; Dew Point: 37F; Wind: S at 11G17 kts Sea-level pressure: 30.08 ins. Hg, falling, then more quickly Visibility: 65 miles 6-hr Max temp: 73F 6-hr Min temp: 60F BHO SA 1755 140 SCT 170 OVC 65 187/69/37/1811G17/008/ FEW CU DSNT WNW-N HIR CLDS VSBL DSNT W-NNE SUN DMLY VSBL VSBY NW 75 LGT DSNT HZ/ 8/177 58016 10073 20060 SUMMARY FOR FRIDAY, MAY 20, 2016 TEMPERATURE (DEGREES F) MAX.....73 NORMAL.....68 MIN.....46 NORMAL.....49 MEAN....60 NORMAL.....58 DEPARTURE FROM 30-YEAR NORMAL..........................+2 TOTAL DEPARTURE FOR THE MONTH.........................-39 [-2.2 DEGREES/DAY] HEATING DEGREE DAYS (SEASON JUL TO JUN) TOTAL HEATING UNITS FOR YESTERDAY...............5 DEPARTURE..........-3 TOTAL HEATING UNITS FOR THE MONTH.............229 DEPARTURE.........+29 TOTAL HEATING UNITS FOR THE SEASON...........5221 DEPARTURE.......-1014 TOTAL HEATING UNITS LAST SEASON TO DATE......6374 DIFFERENCE......-1153 PEAK GUST AND AVERAGE WIND SPEED (MPH) PEAK WIND GUST FOR YESTERDAY...................20 SSE AT 18:08 P.M. ASOS........................20 SSE AT 18:02 P.M. DAVIS.......................19 SE AT 18:05 P.M. RMY 21 FASTEST MILE FOR YESTERDAY.....................14 SSE AT 18:10 P.M. * MAXIMUM 2-MINUTE ASOS AVERAGE..................14 SW AT 11:47 P.M. MAXIMUM 2-MINUTE DAVIS AVERAGE.................14 SE AT 18:09 P.M. AVERAGE WIND SPEED AND DIRECTION..............9.5 WNW ASOS.......................8.7 DAVIS......................8.0 W [260 Deg.] * Last of several occurrences PRECIPITATION (INCHES) THROUGH THIS MORNING (EST) TOTAL PRECIPITATION 24 HRS ENDING 7 A.M....0.00 DEPARTURE......-0.13 ASOS..............0.00 TOTAL PRECIPITATION FOR THE MONTH..........2.14 DEPARTURE......-0.34 ASOS..............2.02 TOTAL PRECIPITATION FOR THE YEAR..........19.08 DEPARTURE......-1.95 ASOS.............19.02 SNOWFALL (INCHES) THROUGH THIS MORNING (EST) TOTAL SNOWFALL 24 HRS ENDING 7 A.M..........0.0 DEPARTURE........0.0 TOTAL SNOWFALL FOR THE MONTH..............TRACE DEPARTURE........0.0 TOTAL SNOWFALL FOR THE SEASON..............57.5 DEPARTURE.......-5.7 PRELIMINARY CLIMATE SUMMARY FOR MAY CALENDAR DAY DATA DATE: MAX/MIN/MEAN/DEP/PRECIP/SUN(MIN.)/SUN(%)/ PEAK GUST/AERO/RMY GUST AERO: Aerovane wind recording system gust RMY: R.M. Young wind gust recording system TSTM: Thunderstorm day (thunder heard some time during day) ....: Data not yet available, records not finalized 5/1 52/39/46/-7/0.08/T/000/00 21 S AERO 22 SE RMY 20 5/2 50/41/46/-7/0.31/0.0/000/00 20 NE AERO 21 NE RMY 18 5/3 48/43/46/-7/0.16/0.0/000/00 16 E AERO 16 E RMY 17 5/4 48/41/45/-9/0.53/0.0/000/00 33 NE AERO 35 NE RMY 34 5/5 44/41/43/-11/0.30/0.0/000/00 39 NNE AERO 41 NNE RMY 39 5/6 54/43/49/-5/0.13/0.0/360/42 28 ENE AERO 29 N RMY 26 5/7 51/43/47/-8/.../0.0/000/00 25 NE AERO 25 NE RMY 23 5/8 60/46/53/-2/.../0.0/284/33 47 W AERO 53 W RMY 49 5/9 65/43/54/-1/0.00/0.0/743/86 40 W AERO 44 W RMY 40 5/10 69/40/55/0/0.00/0.0/806/93 22 W AERO 25 WNW RMY 22 5/11 76/50/63/+7/0.00/0.0/808/93 22 WNW AERO 23 WNW*RMY 22 5/12 75/54/65/+9/0.00/0.0/819/94 23 NNE AERO 25 S RMY 23 5/13 74/52/63/+7/0.21/0.0/079/09 27 S AERO 27 S RMY 26 5/14 78/54/66/+9/0.00/0.0/.../.. 35 SSW*AERO 40 SSW RMY 37 5/15 60/41/51/-6/0.00/0.0/.../.. 50 W AERO 54 W RMY 49 5/16 58/38/48/-9/0.00/0.0/.../.. 45 W* AERO 51 WNW RMY 49 5/17 69/47/58/+1/0.00/0.0/.../.. 32 W AERO 38 W RMY 38 5/18 64/48/56/-2/0.00/0.0/.../.. 24 NE AERO 26 NNW RMY N/A 5/19 66/49/58/0/0.26/0.0/.../.. 23 WNW AERO 26 WNW RMY 25 5/20 73/46/60/+2/0.00/0.0/.../.. 20 SSE AERO 22 SSE RMY 21 5/21 low temp since midnight is 53F; normal low now 49F * Last of several occurrences * All sunshine data corrected to astronomical minutes. DAILY RECORDS FOR MAY 2016 5/1/16: DAILY RECORD SNOWFALL OF A TRACE, TIES PREVIOUS RECORDS SET IN 1905, 1917, 1921, and 1995 DAILY EXTREMES Temperature and precipitation records back to 1885, and wind records back to 1940 (e = estimated): RECORDS FOR MAY 21 HIGH 92F IN 1921 LOW 35F IN 1907 PRECIP 1.61 INS IN 1954 PEAK GUST 74 MPH WSW IN 2006 RECORDS FOR MAY 22 HIGH 93F IN 1911 LOW 35F IN 1907 PRECIP 3.75 INCHES IN 1920 PEAK GUST 49e MPH SSW IN 1947 TODAY'S REPORT PREPARED BY: Mike Iacono